1. Field of the Invention
The present invention relates to a touch detection method and a related optical touch system, and more particularly, to a touch detection method and a related optical touch system capable of using light emission with time division.
2. Description of the Prior Art
Touch screens, which allow a user to perform more intuitive and convenient operations, are widely applied in various consumer electronic products. A general touch screen is composed of a display and a transparent touch board, where the transparent touch board is glued to the display in order to realize both touch and display functions. Among the applications of touch screens, one of the most popular is optical touch technology.
A modern optical touch screen uses 2 sensors for performing 2-point touch or uses 6 sensors for performing 5-point touch. FIG. 1 is a schematic diagram of the structure of a conventional optical touch screen 10. The optical touch screen 10 includes two sensors glued to the upper left corner and upper right corner of the screen, respectively, for monitoring in which positions shadows are located. When a touch occurs, the light is blocked so that shadows are generated on reflection strips (points A, B, C and D in FIG. 1 are shadows). The sensors thereby detect fragments of an optical axis sliced by shadows instead of an entire optical axis. The locations of the shadows are then sent to the system, and coordinates of the touch points can be determined via logic operations. Taking a 2-point touch as an example, a ghost point may occur when there are two touch points on the touch screen. The sensors may monitor four shadows, wherein two of these shadows are fake, since the shadow locations are utilized for determination. Wrong determination may easily occur in two-out-of-four selection. It is essential for modern optical touch screens to achieve multi-touch and ghost point filtering without increasing the number of sensors.